MH Frame = Keel
"Frame" must be one of the most commonly heard MH terms. The Frame is the principal part of the internal skeleton, namely the solid and durable spinal parts, the shoulders that mount the arms (shoulder blade and collarbone), and the hips that take most of the weight and impact.
This large spine, shoulder, and hip assembly is called the "Frame", and termed the "Keel". It has the same meaning as the keel running down the center of a ship's frame.
A MH with the moving parts of its joints and skeleton assembled is called a "Setting Frame (Exoskeletal Stage)", but as this includes some armor Sopp and others may also refer to it as "Primary Armoring". The Jagd Mirage under construction in volume 2 is at the Primary Armoring stage. Hence, arms and legs are not counted in the Frame category.
A MH's Frame refers to just the keel, and the length of the keel determines the size of the MH.
Among MHs, Hathuha's A-Toll and the various Sirens carry some of the longest, heaviest keels and are called Large Frame MH. Keel dimensions are decided by the individual Meights, so there is no standardization. On the other end of the scale, the Engage series use a rather short keel resulting in a small, compact unit.
LED Mirage units use a rather larger keel, but maintain a unit height similar to the Engage. The LED Mirage's needs a heavier keel to accomodate the paired Twin Ezlazer Bypass units.
A large frame therefore does not necessarily imply a taller MH.

Frame Settings ~ Cheetah Type and Lion Type
Frame settings are frequently related to wild animals. The spine's toughness becomes a beast's power, and is reflected thereby. The small cheetah has a bigger spine than its body would imply to provide explosive power to its limbs and absorb impacts, making it capable of reaching speeds over 100km/hr.
The lion capitalizes instead on brute strength and the power of his jaws, trading the cheetah's high speed for the limb and jaw strength to take down large game the cheetah couldn't possibly hunt.
This theory then is transferred directly over to develop the MH's spine and skeleton.
Accordingly, MH built with heavy keels for their armor and unit weight are "Cheetah Type", while ones with a keel balanced for armor and unit weight are "Lion Type".
Cheetah type settings prioritize speed and agility, with a slender armored appearance. Colus's Engage series and the Electroknights' KAN are examples. These frames are powerful and nimble, but lack the Lion type's capability for different armor variations. Essentially they have the disadvantage of a lack of versatility.
The majority of MH are built with Lion type settings, that proportion including such noted MH as the Black Knight, the Berlin, and the Ashra Temple's Temple series, adding up to more than 90% of all MH. Lion types balance power with stability, and with the versatility of supporting variant armorings can be said to be the standard frame settings for a MH.
While these settings are also affected by the power settings of the limb and torso tissue systems, this is not an indication that the keel is specifically light or heavy.
All this is saying is that the final power balance of the frame can be Cheetah typed or Lion typed. The frame alone cannot provide a cheetah's speed or a lion's strength. Engine power must be balanced against armor weight, and a strong engine puts its own stress on the frame, affecting durability and reliability. Adding a management system to the frame to control engine power and the keel's tissue system improves durability but reduces speed and agility, which then requires the reduction of armor and equipment to restore. Balancing all these is incredibly difficult.
Rather than pushing for just "running fast" or "jumping high", meights are constantly worrying about multiple factors. It's about how much to tune mobility and defense and attack power.
The Siren has an abnormally wide tolerance; everything from the tough Arcana Siren to the slender Neptune all share the same main Siren Frame. Rather, the fact that an armor monster like the Arcana Siren can be moved, with its heavy weight and the corresponding shock absorbed by the same frame that the Neptune is using for its high-speed strikes and movement show just how super first-class the Siren Frame is.
The new MH Phantom is based on streamlining this frame to support only heavy and standard combat equipment. There aren't likely to be as many variations as the Siren, but general-purpose and destroyer types are quite possible. It will likely be used alongside the Siren for some time.

He's already mentioned the Engage series and the Kan. I would also guess the A-toll Scritti, the Eleshis, Empress Flame, The Neptune, The Akatsuki-hime (Mighty Alpha), The Suio Maru (Mighty Gamma), the Phantom, and the Siren-R. At first glance I might say the Zakker as well, but it has a heavy armor configuration meaning it's frame was balanced to take additional armor and equipment if necessary, knocking it out of the running for Cheetah type.

So how much faster are Cheetah type MH's than Lion type? And how much "stronger" are Lion type MH's than Cheetah type?

Head joint (Collar bone)
In a similar manner to the human skull, the rear part of the head is fixed to the spine of the main frame. The head and neck are moved up and down, left and right by the collar bone joints.
The two main shafts set between the neck and body seen on most MH have the same capabilities as the equivalent human parts, able to reproduce the complex movements involved in lowering the jaw or tilting the neck.
The MH head itself contains little more equipment than the eyeballs and scanners for exterior data collection. The most important being the "Fatima" brain, the Fatima cockpit is encased in a sturdy capsule called the "Fatima Shell". In order to twist the neck the two shafts are moved in opposite directions to turn the face to the side.

Shoulder joint (Shoulder blade)
The arms are set upon the shoulder blades of the main frame, based at the neck. The shoulder blade, collar bone, and upper arm power cylinders are linked together into an interlocking unit. Unlike a toy robot, the arm is not connected to the body by a single rotating shaft. Like a human, the shoulder itself moves up and down the raise and lower the arm.
The arm to body connection is strongly linked to the shoulder blade and collar bone, with two thick support arms above and below. The reciprocal movement of these arms shifts the upper arm forward and back, left and right. As with a human, the main pivot point is the shoulder blade. If this is damaged the arm can no longer be moved, but between the collar bones alongide the cockpit and the most solid armor on the back, breaking the shoulder blade is next to impossible.
Due to the solidity of the shoulder blade setup, many MH leave this area exposed, as it won't easily be destroyed anyway.
Among the shoulder blade and collar bone is installed the Ezlazer energy converting "Function Turbine", whose exhaust heat is expelled below the shoulder blade. See the later "Engine and Output Management" section.
Please move your own arm and feel the movement of your own collar bone and shoulder blade to confirm how this works. A MH also moves like that under the armor. At the least, have you now understood that a MH's movement is not defined by the exoskeletal form of its armored appearance?

Doing this page in two parts; next is power cylinders. I wonder if Nagano prefers "armored humanoids" over straight mechanical designs because his background in fashion design makes it easier for him to visualize?

Tissue System ~ Joints and Drive System
The drive system serves generally the same purpose as the muscles and tendons in a human body. This is generally called the "tissue system". The most important parts of the tissue system are the shoulder blade internal power cylinders that are the basis of arm movement, the abdominal portion of the keel that twists the body, and the thigh power cylinders that drive the legs.
For the robots of Joker with over a thousand years of history behind them, these three parts are the most important; from the arms to the hands and fingers, knees and heels, put bluntly, are there "just because". While they are a natural progression to the ends of the limbs, their presence does not significantly improve anything.
Essentially, having extras like fingers and heels does not have any real effect on the frame or power figures. There is enough margin to accomodate these without issue. This is evidenced by the presence of heel-less MH walking on their toes (volume 9's Scritti), heels flush with the ground (KOG, etc. up to volume 3), and even dancing around in high-heels (Jagd Mirage). The extremities of the limbs can be chosen according to the knight or meisters preferences without regard to power balance and stability.
The drive system consists of the active parts that move the MH's tendons and pistons, allowing it to reach out and walk. Surprisingly, the particulars of the drive system have never been published, so many people have been left in the dark as to whether the MH joints are run by motors, or the pistons driven by hydraulics or not. Even after all these years, I still find places where I go "huh?" when noticing a lack of explanations.

Power Cylinders
In any case, pretty much everything in a MH is dependent upon "reactive gearing driven by ezlaser energy pressure."
While the joints like the elbow and knee are rotational links, these are not moved by anything like a spinning motor. A motor drive would be unable to produce instantaneous movement; the gearing and cams would be much too complex to suddenly pull a hand back, or rapidly dash into a jump.
The whir and rumble of a motor driving cams in a joint's axis can reproduce only abnormally slow motions. The cams and gears needed to produce the appropriate torque for a joint would make the joint itself unreasonably large, and such a complex joint would no doubt be unable to support its own weight.
While I apologize for going off track with an example, the robot dog that was popular a while back moved using this kind of shafted joint. As a toy, I think it was quite innovative, but this is just an example of the kind of movement you get from a motorized joint. Sorry.

Right, then. MH movements are born from pistons called "power cylinders" which can expand and contract with instantaneous speed. If you'd like, you can think of the variously-shaped cylinders set in a MH as being like a car engine's pistons, moving in and out by combustion. The movement of these pistons can be freely controlled from dreadfully slow to near-lightspeed. The cylinders are driven with the power produced by pushing ezlaser energy into the piston cylinders.
To instantly bend the arm, ezlaser energy is explosively fed to the outside pistons on the upper and lower arms, reproducing the motion of suddenly pulling back the hand. Essentially, this is the same way human muscles move. Obviously, the MH joints and connected cylinders are much more complicated than a human's, but the theory is the same as for these simpler connections.
Conversely, to bend the arm slowly, ezlaser energy would be fed to the same cylinders at a very slow rate, resulting in the cylinders expanding slowly.
To reverse this process and compress these cylinders (therefore extending the arm), we'd use the the opposite side of the arm in the same way that muscles work, simply expanding the inside pistons to compress the outside ones.

Power cylinders are divided into multiple types by purpose:
1. Converting pressure in one direction only, "Single Phase Cylinder"
2. Damper-style with the center of the cylinder reacting to pressure from both ends, "Counter-reactive Cylinder"
3. Converting pressure from the center in both directions, "Bidirectional Cylinder"
4. Splitting partway, can adjust pressure in all directions, "Y-shaped Cylinder"
5. Further adjusting pressure in four directions, "X-shaped Cylinder"

These cylinders, absorbing ezlaser power, are essential to driving a MH.
The cylinder includes only the pressure-converting piston part and the ezlaser energy explosive pressure chamber. As the cylinder is sufficient for movement by itself, there is no need for any further pumps or compressors for hydraulic dampers, or support motors and gearing.
Since power cylinders are the primary driving force, motors and dampers are only used as backups.

The whooshing sound MH are always producing is the sound of energy being fed to these power cylinders, and are the sound of an active MH. The complex linkages of the power cylinders can reproduce the standard movements of bending, stretching, pulling, pushing, twisting, and turning at any speed. See the illustrations for further details.
Further, joints including the neck, base of the shoulder blade, base of the heel, elbow, and secondary joints like the wrist have cams and gearing for motors built-in. In the event that cylinders at drive joints are destroyed, the attached motors can provide backup power and maintain clearance for the armor plating.

Ezlaser Engine
The semi-permanent photon conversion external combustion engine that generates power for the whole MH.
With a maximum instantaneous output over one trillion horsepower, the unimaginable power produced by this engine is said to be such that a full-power sword swing approaches the speed of light, but unlike a car engine, the power from the engine does not flow directly to the pistons and motors of the MH. Generated energy passes through an energy amplifier called the Function Turbine before being sent to the various parts of the MH.
Unfortunately, the Ezlaser engine itself is beyond understanding with our level of science. Further, even were it to be buried for ten thousand years, the engine would have lost none of its energy. The Ezlaser engine is lauded as being the most indestructible of objects.
Awesome as it is, the engine itself is barely one cubic meter in size. This system's effectiveness is simply unrelated to volume. This one cubic meter engine that can run anything from a single MH to a 400 meter plus space battleship probably can't be explained in terms of three dimensional physics.

Ezlaser Function
In addition to amplifying and distributing the energy produced by the engine, the Ezlaser Function System also covers the energy refilling system. This is the foundation of the MH's status as a semi-permanent device.
Energy amplification is handled by the Function Turbine, the interior of which is probably (just a guess) in a state similar to the runaway energy of a new star being born. The amplified energy is then sent around the MH by the function system to move it. The main part of the Ezlaser energy goes into the cylinders of the tissue system, with support energy converted to an electrical charge for the axial motors and system power. Also, energy recovered by the pistons and motors during MH movement is returned to the function turbine, where it becomes a power source for the Ezlaser engine.
Many MH have the Ezlaser engine installed in the torso under the cockpit, generally in the same location as a human's heart. The function turbines are usually installed two per MH on either side of the Ezlaser engine, before the shoulder blades. The position is the same as the lungs in a human. Heat energy from the engine system is generally expelled from the back plating and lower side regions of the chest, but a surprising number of MH release heat from the upper or lower shoulder armor instead.
The Mirage series MH are an exception to the rule in that they have two engines mounted in the lower legs, and the function system is built into the shoulder blades.
Energy is taken from here into the tissue drive system to move the MH, and dynamo regeneration recaptures energy from those movements.
Power and electricity to the cockpit and combat equipment is divided and stored in local condensors. These condensors function independently and are able to operate the cockpit, open escape hatches, and such even if the rest of the MH is destroyed or disabled.

Ezlaser External Combustion System Cutaway
The spheroid in the middle is the core of the Ezlaser system. Energy is emitted through over 360 holes in the core to the receiving cover wrapped around it where the explosive energy is collected. A multitude of pinlike transmission lines from the receiver transmit photons to supply the core. Though rather that conducting energy directly the transmission lines function more as catalysts for the core to absorb photon energy. The outer wall of the receiver similarly houses a multitude of drain lines leading into a pair of energy tubes. Energy is generated in the outer wall tens of thousands of times per second, the disparate pulses combining to produce a wave of energy. The strong random pulsing of the resulting energy wave is mitigated by dividing it into two lines that balance each other out. The interior diameter of this aortic energy line is astonishingly only a single micron across. This 1 micron energy vessel is surrounded by heat dissipating tubing 12cm in diameter. While this tube is still worn down by the Ezlaser engine's energy, its regeneration capability is sufficient to render it semipermanent durability. Similarly, energy is passed along the spinal cord from the Function Turbines to the various terminals, so the keel interior is also sealed with the same heat dissipating medium.

Explanatory text for the Function Turbine illustration was already translated with the Designs 3 text, so next is the Fatima Cockpit.